Oxygen Desaturation Relates To Blood Lactate Changes - An Experimental Ischaemic Trauma Study Using NIRS

Abstract

Near infrared spectroscopy is a non-invasive method which continuously measures the oxidative status of the haemoglobin during different interventions. The methodology of NIRS involves the detection of differences in light absorption from tissue. PURPOSE To determine the relationship of deoxyhaemoglobin and blood lactate changes during a handgrip dynamometer test under ischaemia. METHODS Twelve healthy male subjects (age 34.3±6.12, height 1.82±0.06m; weight 79.7±10.1kg) participated in this study. After a blood pressure cuff was inflated at the upper arm at 20mmHg above the systolic blood pressure subjects were instructed to perform cyclic maximal voluntary contractions for one minute using a handgrip dynamometer. After one minute the cuff was deflated. Blood samples were taken from the v. cubitalis after 1, 2, 4, 6 and 10 minutes. NIRS signals were obtained by a probe overlying the forearm flexors. Oxyhaemoglobin and deoxyhaemoglobin values at a depth of up to 25 mm were recorded. The differences in deoxyhaemoglobin (Hb) before and after exercise were calculated and compared to the relative blood lactate changes after 1, 2, 4, 6 and 10 minutes. RESULTS The present findings demonstrated moderate to high linear relationships between relative O2 consumption and blood lactate changes (r = 748, p < 0.05 to r = 863, p < 0.01). Average deoxyhaemoglobin and lactate values are shown in table 1.TableCONCLUSIONS The results illustrate the interrelation between muscle metabolism, reflected by blood lactate, and O2 desaturation. Muscle deoxygenation measured by near infrared spectroscopy could help to predict blood lactate changes and to evaluate the muscular status and exercise capacity.